Articles in 2015

A study now demonstrates that ephrin-B3 recruits and stabilizes PSD-95 at excitatory synapses by direct interaction. Unusually, phosphorylation of ephrin-B3, elicited by neuron depolarization, inhibits this interaction.

The serotonin 1A receptor expressed on mature granule cells in the dentate gyrus mediates the behavioral, neurogenic and endocrine effects of the antidepressant fluoxetine in the mouse.

Previous experiments have suggested that many P2X family channels undergo a time-dependent process of pore dilation when activated by ATP. Li et al. now propose a different interpretation of the key experiments.

Complex demographic and behavioral phenotypes can arise from coordinated interactions among brain systems. A single axis of co-variation spanning 'negative' and 'positive' attributes links diverse participant characteristics with specific patterns of brain connectivity.

Measuring brain connections in humans continues to pose challenges despite the recent advances in MRI technology. The authors contrast methods used in humans with those used in animals and show the extent to which human techniques can inform us about connections despite their limitations.

There is growing realization that glia actively signal with neurons and influence synaptic development, transmission and plasticity through an array of secreted and contact-dependent signals. We propose that disruptions in neuron-glia signaling contribute to synaptic and cognitive impairment in disease.

Hippocampal place cells are active offline in ‘replay’ sequences reflecting speeded-up depictions of behavioral trajectories, suggesting a model of memory. The authors show that encoding of replay sequences requires behavioral experience and the activation of molecular mechanisms of synaptic plasticity, while retrieval does not.

By optogenetically silencing thalamus, the authors show that visual cortex does not sustain a response without thalamus for more than a few tens of milliseconds. This rapid cortical activity decay predicts the temporal dynamics of sensory activity transmission between thalamus and cortex in awake animals, whereas under anesthesia, the fidelity of thalamo-cortical connection is dominated by the effect of synaptic depression.

Stroke is the leading cause of adult disability. This study shows that the secreted factor GDF10 is a signal for the formation of new brain connections that lead to recovery after stroke and can be manipulated to enhance recovery and movement control in this disease.

Using functional MRI and a novel model-based analysis, the authors find that the uncertainty in sensory representations can reliably be estimated from trial-by-trial activity in human visual cortex. Moreover, this uncertainty represented in cortical activity affects the way people make decisions.

PSD-95 is one of the most abundant proteins at synapses and underlies synapse development and function. Hruska and colleagues show that the synaptic localization and turnover of PSD-95 relies on a direct interaction with the trans-synaptic organizer ephrin-B3, which is negatively regulated by neuronal activity through MAPK-dependent phosphorylation of ephrin-B3.

The authors show that episodic-memory representations progressively increase in scale along the hippocampal long axis, akin to the gradient of encoded space in the rodent hippocampus. They propose that this coding mechanism may enable the formation of memory hierarchies.

Increased signal-to-noise in neural representations of sensory stimuli is thought to underlie the perceptual benefits of attention. Manipulating reward contingencies across two locations dissociates visual cortical activity from attentional behavior. These data argue that attention works by selecting and filtering the relevant and irrelevant information represented in visual cortex.

The amygdala is known to process information about faces, but it has remained unclear whether eye gaze is also encoded. Recording single neurons in the amygdalae of neurosurgical patients, the authors found responses to identity of the faces, but not to gaze direction.

Anorexia nervosa provides a compelling example of persistent maladaptive behavior: the severe restriction of caloric intake. Activity in the dorsal striatum was greater in patients than in controls during food choice and correlated with subsequent caloric intake, suggesting that dorsal fronto-striatal circuits are involved in this disorder.

The authors used trans-synaptic tracing to examine and compare circuit anatomy in mouse barrel and medial prefrontal cortex, revealing novel organizational features and contrasts between the two areas. Notably, medial prefrontal layer 5 neurons receive more long-distance inputs and more local inhibitory inputs than layer 5 neurons in barrel cortex.

This study shows that every individual has a unique pattern of functional connections between brain regions. This functional connectivity profile acts as a ‘fingerprint’ that can accurately identify the individual from a large group. Furthermore, an individual's connectivity profile can predict his or her level of fluid intelligence.

Sleeping mammalian brains show high coherence of slow-wave activity. In mouse models of Alzheimer's disease, which have abnormal levels of amyloid-β, amyloid plaques and associated memory deficits, these waves are massively impaired. This impairment is related to the previously demonstrated neuronal hyperactivity. Pharmacological manipulations that reduce hyperactivity result in the reinstatement of slow-wave coherence and in memory improvement.